1. Field of the Invention
The present disclosure relates to adaptive sampling and is more particularly, although not exclusively concerned with the adaptive sampling of biopotential signals.
2. Description of the Related Technology
Power efficiency of readout circuits for ambulatory monitoring of biopotential signals has been significantly improved during recent years, leaving digital signal processing and wireless transmission dominating the system power. One of the key problems of the current wireless biomedical systems is the vast amount of data that needs to be processed by a digital signal processor (DSP) and/or that needs to be transmitted over the wireless link. Such a vast amount of data considerably limits the power autonomy of these systems. Therefore, the compression of data is gaining more attention for reducing the amount of processing and the data transmitted over the wireless link.
The sampling rate of biopotential signals and, more in particular, those of ECG signals, is conventionally selected according to the bandwidth of the signal, which is defined by the QRS complex part of the ECG trace In addition, some diagnostic tools such as heart rate variability (HRV) analysis, may require even higher sampling rate due to the required time resolution to precisely find the R point in the QRS complex. However, such high and constant sampling rate over the entire ECG signal significantly increases the data rate and leads to increasing power dissipation.
Commonly portable biopotential monitoring systems follow one of two approaches:                1. The signals are processed in the system and the results are transmitted; or        2. The signals are continuously streamed and the processing takes place at the receiver side.        
The first type of system can make use of data compression to reduce DSP work load. The second type of system can benefit from data compression by transmitting significantly less data.